vorbis/examples/decoder_example.c

   1 /********************************************************************
   2  *                                                                  *
   3  * THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE.   *
   4  * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *
   5  * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
   6  * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *
   7  *                                                                  *
   8  * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2009             *
   9  * by the Xiph.Org Foundation http://www.xiph.org/                  *
  10  *                                                                  *
  11  ********************************************************************
  12
  13  function: simple example decoder
  14  last mod: $Id$
  15
  16  ********************************************************************/
  17
  18 /* Takes a vorbis bitstream from stdin and writes raw stereo PCM to
  19    stdout. Decodes simple and chained OggVorbis files from beginning
  20    to end. Vorbisfile.a is somewhat more complex than the code below.  */
  21
  22 /* Note that this is POSIX, not ANSI code */
  23
  24 #include <stdio.h>
  25 #include <stdlib.h>
  26 #include <math.h>
  27 #include <vorbis/codec.h>
  28
  29 #ifdef _WIN32 /* We need the following two to set stdin/stdout to binary */
  30 #include <io.h>
  31 #include <fcntl.h>
  32 #endif
  33
  34 #if defined(__MACOS__) && defined(__MWERKS__)
  35 #include <console.h>      /* CodeWarrior's Mac "command-line" support */
  36 #endif
  37
  38 ogg_int16_t convbuffer[4096]; /* take 8k out of the data segment, not the stack */
  39 int convsize=4096;
  40
  41 extern void _VDBG_dump(void);
  42
  43 int main(){
  44   ogg_sync_state   oy; /* sync and verify incoming physical bitstream */
  45   ogg_stream_state os; /* take physical pages, weld into a logical
  46                           stream of packets */
  47   ogg_page         og; /* one Ogg bitstream page. Vorbis packets are inside */
  48   ogg_packet       op; /* one raw packet of data for decode */
  49
  50   vorbis_info      vi; /* struct that stores all the static vorbis bitstream
  51                           settings */
  52   vorbis_comment   vc; /* struct that stores all the bitstream user comments */
  53   vorbis_dsp_state vd; /* central working state for the packet->PCM decoder */
  54   vorbis_block     vb; /* local working space for packet->PCM decode */
  55
  56   char *buffer;
  57   int  bytes;
  58
  59 #ifdef _WIN32 /* We need to set stdin/stdout to binary mode. Damn windows. */
  60   /* Beware the evil ifdef. We avoid these where we can, but this one we
  61      cannot. Don't add any more, you'll probably go to hell if you do. */
  62   _setmode( _fileno( stdin ), _O_BINARY );
  63   _setmode( _fileno( stdout ), _O_BINARY );
  64 #endif
  65
  66 #if defined(macintosh) && defined(__MWERKS__)
  67   {
  68     int argc;
  69     char **argv;
  70     argc=ccommand(&argv); /* get a "command line" from the Mac user */
  71                      /* this also lets the user set stdin and stdout */
  72   }
  73 #endif
  74
  75   /********** Decode setup ************/
  76
  77   ogg_sync_init(&oy); /* Now we can read pages */
  78
  79   while(1){ /* we repeat if the bitstream is chained */
  80     int eos=0;
  81     int i;
  82
  83     /* grab some data at the head of the stream. We want the first page
  84        (which is guaranteed to be small and only contain the Vorbis
  85        stream initial header) We need the first page to get the stream
  86        serialno. */
  87
  88     /* submit a 4k block to libvorbis' Ogg layer */
  89     buffer=ogg_sync_buffer(&oy,4096);
  90     bytes=fread(buffer,1,4096,stdin);
  91     ogg_sync_wrote(&oy,bytes);
  92
  93     /* Get the first page. */
  94     if(ogg_sync_pageout(&oy,&og)!=1){
  95       /* have we simply run out of data?  If so, we're done. */
  96       if(bytes<4096)break;
  97
  98       /* error case.  Must not be Vorbis data */
  99       fprintf(stderr,"Input does not appear to be an Ogg bitstream.\n");
 100       exit(1);
 101     }
 102
 103     /* Get the serial number and set up the rest of decode. */
 104     /* serialno first; use it to set up a logical stream */
 105     ogg_stream_init(&os,ogg_page_serialno(&og));
 106
 107     /* extract the initial header from the first page and verify that the
 108        Ogg bitstream is in fact Vorbis data */
 109
 110     /* I handle the initial header first instead of just having the code
 111        read all three Vorbis headers at once because reading the initial
 112        header is an easy way to identify a Vorbis bitstream and it's
 113        useful to see that functionality seperated out. */
 114
 115     vorbis_info_init(&vi);
 116     vorbis_comment_init(&vc);
 117     if(ogg_stream_pagein(&os,&og)<0){
 118       /* error; stream version mismatch perhaps */
 119       fprintf(stderr,"Error reading first page of Ogg bitstream data.\n");
 120       exit(1);
 121     }
 122
 123     if(ogg_stream_packetout(&os,&op)!=1){
 124       /* no page? must not be vorbis */
 125       fprintf(stderr,"Error reading initial header packet.\n");
 126       exit(1);
 127     }
 128
 129     if(vorbis_synthesis_headerin(&vi,&vc,&op)<0){
 130       /* error case; not a vorbis header */
 131       fprintf(stderr,"This Ogg bitstream does not contain Vorbis "
 132               "audio data.\n");
 133       exit(1);
 134     }
 135
 136     /* At this point, we're sure we're Vorbis. We've set up the logical
 137        (Ogg) bitstream decoder. Get the comment and codebook headers and
 138        set up the Vorbis decoder */
 139
 140     /* The next two packets in order are the comment and codebook headers.
 141        They're likely large and may span multiple pages. Thus we read
 142        and submit data until we get our two packets, watching that no
 143        pages are missing. If a page is missing, error out; losing a
 144        header page is the only place where missing data is fatal. */
 145
 146     i=0;
 147     while(i<2){
 148       while(i<2){
 149         int result=ogg_sync_pageout(&oy,&og);
 150         if(result==0)break; /* Need more data */
 151         /* Don't complain about missing or corrupt data yet. We'll
 152            catch it at the packet output phase */
 153         if(result==1){
 154           ogg_stream_pagein(&os,&og); /* we can ignore any errors here
 155                                          as they'll also become apparent
 156                                          at packetout */
 157           while(i<2){
 158             result=ogg_stream_packetout(&os,&op);
 159             if(result==0)break;
 160             if(result<0){
 161               /* Uh oh; data at some point was corrupted or missing!
 162                  We can't tolerate that in a header.  Die. */
 163               fprintf(stderr,"Corrupt secondary header.  Exiting.\n");
 164               exit(1);
 165             }
 166             result=vorbis_synthesis_headerin(&vi,&vc,&op);
 167             if(result<0){
 168               fprintf(stderr,"Corrupt secondary header.  Exiting.\n");
 169               exit(1);
 170             }
 171             i++;
 172           }
 173         }
 174       }
 175       /* no harm in not checking before adding more */
 176       buffer=ogg_sync_buffer(&oy,4096);
 177       bytes=fread(buffer,1,4096,stdin);
 178       if(bytes==0 && i<2){
 179         fprintf(stderr,"End of file before finding all Vorbis headers!\n");
 180         exit(1);
 181       }
 182       ogg_sync_wrote(&oy,bytes);
 183     }
 184
 185     /* Throw the comments plus a few lines about the bitstream we're
 186        decoding */
 187     {
 188       char **ptr=vc.user_comments;
 189       while(*ptr){
 190         fprintf(stderr,"%s\n",*ptr);
 191         ++ptr;
 192       }
 193       fprintf(stderr,"\nBitstream is %d channel, %ldHz\n",vi.channels,vi.rate);
 194       fprintf(stderr,"Encoded by: %s\n\n",vc.vendor);
 195     }
 196
 197     convsize=4096/vi.channels;
 198
 199     /* OK, got and parsed all three headers. Initialize the Vorbis
 200        packet->PCM decoder. */
 201     if(vorbis_synthesis_init(&vd,&vi)==0){ /* central decode state */
 202       vorbis_block_init(&vd,&vb);          /* local state for most of the decode
 203                                               so multiple block decodes can
 204                                               proceed in parallel. We could init
 205                                               multiple vorbis_block structures
 206                                               for vd here */
 207
 208       /* The rest is just a straight decode loop until end of stream */
 209       while(!eos){
 210         while(!eos){
 211           int result=ogg_sync_pageout(&oy,&og);
 212           if(result==0)break; /* need more data */
 213           if(result<0){ /* missing or corrupt data at this page position */
 214             fprintf(stderr,"Corrupt or missing data in bitstream; "
 215                     "continuing...\n");
 216           }else{
 217             ogg_stream_pagein(&os,&og); /* can safely ignore errors at
 218                                            this point */
 219             while(1){
 220               result=ogg_stream_packetout(&os,&op);
 221
 222               if(result==0)break; /* need more data */
 223               if(result<0){ /* missing or corrupt data at this page position */
 224                 /* no reason to complain; already complained above */
 225               }else{
 226                 /* we have a packet.  Decode it */
 227                 float **pcm;
 228                 int samples;
 229
 230                 if(vorbis_synthesis(&vb,&op)==0) /* test for success! */
 231                   vorbis_synthesis_blockin(&vd,&vb);
 232                 /*
 233
 234                 **pcm is a multichannel float vector.  In stereo, for
 235                 example, pcm[0] is left, and pcm[1] is right.  samples is
 236                 the size of each channel.  Convert the float values
 237                 (-1.<=range<=1.) to whatever PCM format and write it out */
 238
 239                 while((samples=vorbis_synthesis_pcmout(&vd,&pcm))>0){
 240                   int j;
 241                   int clipflag=0;
 242                   int bout=(samples<convsize?samples:convsize);
 243
 244                   /* convert floats to 16 bit signed ints (host order) and
 245                      interleave */
 246                   for(i=0;i<vi.channels;i++){
 247                     ogg_int16_t *ptr=convbuffer+i;
 248                     float  *mono=pcm[i];
 249                     for(j=0;j<bout;j++){
 250 #if 1
 251                       int val=floor(mono[j]*32767.f+.5f);
 252 #else /* optional dither */
 253                       int val=mono[j]*32767.f+drand48()-0.5f;
 254 #endif
 255                       /* might as well guard against clipping */
 256                       if(val>32767){
 257                         val=32767;
 258                         clipflag=1;
 259                       }
 260                       if(val<-32768){
 261                         val=-32768;
 262                         clipflag=1;
 263                       }
 264                       *ptr=val;
 265                       ptr+=vi.channels;
 266                     }
 267                   }
 268
 269                   if(clipflag)
 270                     fprintf(stderr,"Clipping in frame %ld\n",(long)(vd.sequence));
 271
 272
 273                   fwrite(convbuffer,2*vi.channels,bout,stdout);
 274
 275                   vorbis_synthesis_read(&vd,bout); /* tell libvorbis how
 276                                                       many samples we
 277                                                       actually consumed */
 278                 }
 279               }
 280             }
 281             if(ogg_page_eos(&og))eos=1;
 282           }
 283         }
 284         if(!eos){
 285           buffer=ogg_sync_buffer(&oy,4096);
 286           bytes=fread(buffer,1,4096,stdin);
 287           ogg_sync_wrote(&oy,bytes);
 288           if(bytes==0)eos=1;
 289         }
 290       }
 291
 292       /* ogg_page and ogg_packet structs always point to storage in
 293          libvorbis.  They're never freed or manipulated directly */
 294
 295       vorbis_block_clear(&vb);
 296       vorbis_dsp_clear(&vd);
 297     }else{
 298       fprintf(stderr,"Error: Corrupt header during playback initialization.\n");
 299     }
 300
 301     /* clean up this logical bitstream; before exit we see if we're
 302        followed by another [chained] */
 303
 304     ogg_stream_clear(&os);
 305     vorbis_comment_clear(&vc);
 306     vorbis_info_clear(&vi);  /* must be called last */
 307   }
 308
 309   /* OK, clean up the framer */
 310   ogg_sync_clear(&oy);
 311
 312   fprintf(stderr,"Done.\n");
 313   return(0);
 314 }